On Fri, 5 Dec 2003, pervect wrote:

A week or so ago I saw a rather neat Junkyard Wars episode on
pulse-jets. I'm also rather intrigued that it was felt to be a safe
enough gadget to build for the TV show.

Safe enough if you wear earplugs, and don't stand in line with it, but
that applies to other jet engines too.

It was an amazingly simple contraption, a jet with no moving parts.

Actually, most of them have moving parts in the intake end; reed valves or
spring-loaded flaps. Without those you wouldn't have much of an engine,
it'd just sit there and fart flame out both ends.
I
was wondering where I could find out more about the history of these
devices, and perhaps some information as to why they are apparently
outdated and no longer in use. I believe they were used in the V2
rockets in WWII (?).

No, V2 was a true rocket carrying its own liquid oxygen supply. You're
thinking of V1, the buzz-bomb, which was the world's first cruise missle.
Strictly a low-altitude airbreather, but cheap and rugged.

Pulse-jets are a ton of fun for amateurs, but never caught on for large
craft. They tend to shake their airframes brutally, and they go through a
lot of fuel compared to turbojets. Incidentally, if you ever check out a
British movie called Operation Crossbow, it features Sophia Loren as Hanna
Reitsch, test-flying a piloted prototype of the V1.

I don't have the URL's right now, but I did a search a few years ago that
turned up everything from blueprints to references to a model engine that
was sold back in the Fifties. Ear-shattering noise, and it turns red hot
if it's bench-fired without a slipstream to cool it, but it's got a hell
of a power-weight ratio and is very thought-provoking device if you want
to write an alternative history story. The Tredegar Iron Works could have
built the damn things, or even the more advanced shops of Napoleon's day.

Conrad Hodson